1. Field of the Invention
This invention relates to valves and in particular to solenoid-operated cartridge valves.
2. Description of the Prior Art
In one form of fluid flow control valve, a poppet is seated against a valve seat to close the valve. The poppet is provided with a through bore which is selectively closed by a pilot valve. The poppet is spring-biased to the closed position with fluid pressure acting on opposite sides of the poppet so as to permit the spring biasing to maintain the poppet closed. When the pilot valve is raised from the valve seat, the fluid pressure behind the poppet is relieved to the through bore, thus permitting the fluid pressure acting upwardly on the poppet to move the poppet from the valve seat and thereby permit flow through the valve.
In one form, the pilot valve is operated by a suitable solenoid having a plunger connected to the pilot valve for selective positioning thereof in effecting the desired fluid flow control.
Such valves are provided in a wide range of sizes depending on the flow capacity desired.
It is further conventional to provide such valves in the form of cartridges, including both the valve and the solenoid operator in a single assembly which, illustratively, may be connected to suitable ports by a threaded adapter portion thereof.